Froth flotation process



Sept. 17, 1957 0.. R. BROWN 2,806,598

FROTH FLOTATION PROCESS Filed June 15, 1954 FEED l l I I 0 i SORUB u REAGE/VTS IN CONTROLLED AMOUNT r0 GIVE MAX/MUM DESL/ME GRADE AND RECO VERY 0F FINES AND EASILY FLOA TED COARSER MA TER/AL c0/v0/r/0/v FLOAT con/c. *7.

REAGENTS //v AMOUNT r0 F GIVE HIGH RECOVERY OF REMAIN/N6 VALUES.

UNDERFLOW 0L ASS/FICAT/ON OVE FLOW c0/v0/r/0/v [FL OAT? 3 TAIL co/vc. 2.

IINVENTOR.

OTTO R. BROWN,

' AT70RIVEK United States Patent FROTH FLOTATION PROCESS Otto R. Brown, Sacramento, Califl, assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine Application June 15, 1954, Serial No. 436,811 1 Claim. (Cl. 209-166) This invention relates to the beneficiation of ores, particularly glass sand and more particularly is concerned with an improved froth flotation process utilizing two or more stages of conditioning and flotation.

Froth flotation processes for the beneficiation of ores are, of course, well known and are in widespread use in the recovery of the desired minerals or mineral values from ores.

The present invention is based upon the discovery that if the ore is subjected to multiple stages of conditioning with intermediate stages of classification and flotation, it is possible not only to obtain improved metallurgy by way of higher grade of concentrate or by way of better recovery, or both, but it is also possible to obtain such advantages by a marked reductionin reagent consumption and cost.

Essentially, this is accomplished by conditioning the ore, which may have received suitable prior treatment as by grinding, scrubbing and desliming, at preferably high solids, with a controlled amount of reagents so adjusted as to quantity as to permit maximum grade and recovery of the fines and the more easily floated coarser material. The conditioned material is diluted to flotation density and a primary float is made with emphasis on grade rather than on recovery. The tailing from this float is then subjected to a classification operation in a suitable apparatus and is classified into underflow and overflow portions. The overflow portions, which interfere with the oiling of the coarser particles in the underflow, are removed in this classification. The underflow, or coarser size fraction from the classifying apparatus, is conditioned, again preferably at high solids, with an added quantity of reagents in amounts suflicient to permit high recovery of the remaining coarser sizes of mineral values. The overflow from the preceding classification operation is now joined with the discharge from the second conditioning operation and the combined product is subjected to a second stage of flotation, in which the fine minerals not floated in the first stage, as well as the remaining coarser sizes, are recovered. The concentrate from this second float may be joined with the concentrate from the first float or it may receive separate handling. The tailing from the second flotation may constitute the finished product, or it may in turn receive one or more additional treatments in accordance with the previously described procedure.

The principal advantages of the described multiplestage classification, conditioning and flotation are, first, that better selectivity and recovery of mineral values are obtained when these are present in a wide range of sizes, and second, by effecting a classification of the flotation tailing and removing the overflow portion, it is possible to effect a considerable economy in reagent consumption in the oiling of the coarse particles in the underflow since the fines of the overflow are not present to interfere with the oiling of the coarse particles. Moreover, after the oiling has been accomplished, the return of the fines to the circuit so as to be floated with the coarse material in the ensuing float has the added advantage that not only may coarse particles in the fines be floated, but the re- 2,806,598 Patented Sept. 17, 1957 sidual frother and promoter associated with the fines can be used in part as the reagents for the second float and thus reduce the overall reagent consumption.

The accompanying drawing shows diagrammatically a suitable flow sheet illustrating the hereindescribed invention. It is to be understood that even though the above description and accompanying drawing relates generally to two stages of classification, conditioning and flotation, it is obvious that additional stages of classification, conditioning and flotation could be utilized if desired.

It is also to be understood that the froth flotation process of the present invention is applicable to the beneflcation of any sulfide or nonsulfide minerals, particularly where high solids conditioning is required for activation of the minerals such as, for example, glass sands flotation for the removal of heavy minerals, iron ore flotation for the rejection of silica, cement rock for the rejection of silica, alumina and alkalies, etc.

Although high solids conditioning is beneficial in the case of certain types of ores, it may not be essential on others. dilute the deslimed tailings to produce a lower-solids pulp for conditioning with reagents prior to flotation. It is also to be understood that the invention is in no Way limited to the use of any particular reagent or combination of reagents. The-reagents used are of the conventional type for the minerals to be floated.

The invention will be described in greater detail in conjunction with the following specific examples.

Example 1 I 'A cement rock from a California quarry was ground to minus 35 mesh and deslimed. The sand fraction was conditioned for 2 minutes at 55% solids with 0.06 lb./ton of saponified tall oil and with 0.10 lb./ton of sulfonated refined tall oil. The conditioner discharge was then diluted to flotation density, 25% solids, and floated. The tailings from this float were deslimed in a cyclone deslimer and the overflow portion was removed and saved. The sand underflow from the deslimer was conditioned for two minutes at 55 solids with the same quantity of reagents as used in the first conditioning stage. The overflow from the deslimer was then joined with the discharge from the second conditioning stage, diluted to 25% solids and floated. A third conditioning, classification and flotation of the sands was then carried out utilizing the same conditions of density and quantity of reagents as in the first and second conditioning and flotation stages. The metallurgical results obtained were as follows:

Percent Grade, Recovery, Product Weight Percent Percent 0&003 C3003 0 54.0 100.0 53 9 90.0 88. 9 Sand Tail 40.1 13. 4 11.1

A conventional single stage conditioning and flotation operation was carried out on the same cement rock after grinding to minus 35 mesh and desliming utilizing 0.25 lb./ton of saponified tall oil and 0.50 lb./ton of sulfonated refined tall oil. The metallurgical results were as follows:

Percent Grade, Recovery, Product Weight Percent Percent C8003 CaC O;

In some instances it may even be desirable to.

The above data show that with the multiple stage conditioning, classification and flotation procedure of the present invention, the grade of the calcium carbonate obtained was raised from 77.0 to 90.0. Also the reagent consumption in the improved method was reduced from 0.75 lb./ton to 0.48 lb./ton.

Example 2 operation. The metallurgical results obtained were as follows:

Percent Grade, Product Weight Percent Heads-1st Float 1. 78 Heads-2nd Float 100.0 0.025 Heavy Mineral Cone 3.0 Glass Sand Tail 97.0 0. 012

Conventional single-stage conditioning and flotation produced only 90.8% of the weight into a glass sand product assaying 0.025% FezOa, a grade unsuitable for certain special market requirements.

I claim:

A process of beneflciating glass sand which permits optimum grade and recovery with minimum reagent usage, including reducing the iron oxide content, which comprises conditioning at high solids an aqueous pulp of the glass sand with only suflicient reagents to permit maximum separation of the finer sizes of impurities and the more easily floatable coarser impurities, diluting the conditioned pulp to flotation density and subjecting the pulp to a primary float, classifying the tailing from the primary flotation into a fine overflow fraction and a coarse underflow fraction, removing the overflow fraction, conditioning at high solids the underflow fraction with sufiicient additional reagents so that when used with the reagents recycled with the fines there results good separation of the remaining impurities, joining the overflow fraction containing fines, water and residual reagent from the classifier discharge with the conditioned underflow, subjecting the combined product to a second flotation operation, separating out the floated impurities, and recovering the purified glass sand tailings from the second operation, whereby lesser reagents are required than .in

a single step to obtain a given grade and recovery, and

whereby the glass sand tailings recovered have not more than 0.012% ferric oxide therein.

References Cited in the file of this patent A. I. M. M. E. Technical Publication No. 414, Effect of Particle Size on Flotation, by Gaudin et 2.1., 1931, 23 pages.

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